1. Field of Invention
The present invention relates generally to a solder composition and, more particularly, to a solder composition for assembling, repairing and/or sizing jewelry having a platinum content of up to about 95% by weight.
The present invention also relates generally to a solder composition and, more particularly, to a solder composition for assembling, repairing and/or sizing jewelry having a silver content of at least 92.5% by weight, and the balance being made of an alloy consisting of gallium, indium and copper in respective ratios of 6:3:1.
The present invention also relates generally to a solder composition and, more particularly, to a solder composition for assembling, repairing and/or sizing jewelry having a gold content of about 25% to about 91.6% by weight, and a mixture of other metals including about 8% to about 80% silver, about 1% to about 66% copper, about 5% to about 31% zinc and about 0% to about 35% nickel, said solder composition consisting of 2–14% gallium, indium and copper, in respective ratios of 6:3:1.
A platinum or silver alloy consisting of gallium, indium and copper is used to lower the melting point of platinum and silver to provide a solder composition having a reduced melting point.
A gold alloy consisting one or more metals including silver, copper, zinc or nickel and further consisting of gallium, indium and copper to provide a solder composition having a reduced melting point.
More particularly, the platinum solders have melting temperatures in a range from about 1300° C. (2372° F.) to about 1500° C. (2732° F.), and the gold and silver solders melting temperatures in a range from about 1000° F. (538° C.) to about 1400° F. (760° C.).
2. Description of the Related Art
A variety of solder compositions are known in the art for repairing platinum, silver and gold jewelry. These prior art compositions are characterized by melting temperatures ranging from about 1000° C. to about 1700° C. and consist essentially of varying relative amounts by weight of gold, silver and/or palladium. The higher melting temperature solder compositions (1600° C. and 1700° C.) are difficult to work with and have melting temperatures that are not significantly lower than the melting temperature of pure platinum (1769° C.). While the lower melting temperature compositions are easier to work with than the higher melting temperature compositions, all of the compositions are problematic when used to repair platinum jewelry having a platinum content of at least 90% by weight. Specifically, the color of the solder composition does not match the color of the high platinum content jewelry. This results in an unsightly dark seam or spot of solder that must be temporarily masked by plating the seam or spot with rhodium. In addition to adding to the cost and complexity of the jewelry repair, the rhodium plating is also subject to wear over time, whereupon the color difference between the platinum jewelry and the solder composition becomes visible again. Moreover, pitting of the solder at its point of application to the jewelry is often observed, thus further detracting from the appearance of the repaired jewelry.
It is known to add minor amounts of platinum (up to about 5% by weight) to the above-noted solder compositions, but the problems of color matching and pitting still persist. Solder compositions combining palladium and up to 75% by weight platinum have also been employed, but such compositions are characterized by high melting temperatures (1600° C. to 1700° C.) that are not significantly lower than the 1769° C. melting temperature of platinum itself and make the compositions difficult to work with. Additionally, color matching and pitting problems still occur.
Various high platinum content jewelry materials are known in the art. For example, U.S. Pat. No. 4,165,983 discloses an alloy for fabricating jewelry containing at least 95% by weight platinum, 1.5% to 3.5% by weight gallium, and a balance of at least one of indium, gold, palladium, silver, copper, cobalt, nickel, ruthenium, iridium and rhodium. U.S. Pat. No. 5,846,352 discloses a heat-treated platinum-gallium alloy for fabricating jewelry containing 1% to 9% by weight gallium and a small amount of palladium. However, such alloys are intended for fabricating the jewelry itself. Neither of these patents disclose or suggest particular solder compositions that would be useful for repairing platinum jewelry, and particularly platinum jewelry having a platinum content of up to about 95% by weight.
The standard of fineness for silver products is sterling or standard silver (92.5%). The other 7.5% of the silver alloy content can be any metal but it is usually copper. Similarly, karat gold is an alloy of gold with other metals. Pure gold is very soft unless alloyed into a karat gold such as 18 karat (75% pure) or 22 carat (91.6% pure). The gold alloys may contain several other metallic elements including copper, silver, nickel and zinc to vary the color, the hardness and the melting points.
Currently, there are no known solder compositions for platinum, silver and gold alloys with low flow temperatures that can be used for repairing jewelry having a platinum content of at least 90% by weight, having a silver content of at least 92.5% by weight, and having a gold content of at least 25% to about 91.6% by weight without incurring the above-mentioned problems. Accordingly, the development of a solder composition for such platinum, silver and gold jewelry that does not involve the aforementioned problems would be a significant advance in the art.